1. Field of the Invention
This invention relates to integrated circuit technology and, more specifically, to antifuse structures and methods of fabrication thereof which provide a connection in a permanent physical connection between two previously unconnected circuit locations.
2. Brief Description of the Prior Art
Programmable integrated circuits have been developed which allow the user to program the integrated circuit to a specific need. A type of programmable device is a field programmable gate array (FPGA). These devices provide large arrays of fusible type structures on a substrate which allow the user to program the functional operation of the devices by altering the conductive state of these fusible devices. One such fusible device is called an antifuse. An antifuse operates in the opposite manner to that of a traditional fuse in that it is programmed by providing a voltage above a threshold determined by the characteristics of the device which causes a large current to pass between two conductive layers separated by a dielectric layer. After this threshold voltage has been reached, the dielectric breaks down and a conductive connection is established between the two conductive layers via a filament formed through an aperture in the dielectric layer.
Also, due to limitations presently inherent in the photolithographic procedures available, the dimensions of the fuse are not reducible to the extent desirable, hence leading to larger than desired capacitance in the fuse region. These capacitances result in large RC delays in high frequency applications, as is well known.